Ignition system



April 7, 1942.

J. J. ROSE 2,278,490

IGNITION SYSTEM Filed May 26, 1938 4 Sheets-Sheet l Array/veg:

April 7, 1942. J. J.- ROSE IGNITION SYSTEM Filed May 26, 1938 4Sheets-Sheet 2 Avmswrae PO 8 &

April 7, 1942.

J. J. ROSE IGNITION SYSTEM Filed May 26, 1938 27 v Avme/vrae 28 7 g/.Pose;

4 Sheets-Sheet 3 I April 7, 1942.

J. J. ROSE IGNITION SYSTEM 4 Sheets-Sheet 4 Filed May 26, 1938 PatentedApr. 7, 1942 UNITE IGNITION SYSTEM John .7. Rose, Dayton, Ohio PApplication May 26, 1938, Serial No. 210,250

(Granted under the act of March 3, 1883, as

amended April so, 1928; 370 o. G. 757) '7 Claims.

me of any royalty thereon.

My invention relates to internal combustion engines of the articulatingpiston connecting rod type and has for its main object to provide anovel ignition system whereby an ideal relationship is. obtained betweenthe piston positions and the time of firing.

It is well known that, where articulating rods are pivotally connectedto an articulating master rod at points remote from the crank-pin, the'pivot points of the articulating rods trace elliptical paths while thecrank-pin traces a circle, this difierence resulting in an out of phasesyxnmetry relation of the pistons.

Because of this phenomenon, it will be seen that, if articulating rodsof equal length, to which the pistons of an engine are connected at oneend,

.are virtually connected to a master connecting rod at pointsequi-distant from and equi'angularly arranged about the enginecrank-pin, and if the cylinders of the engine are equiangularly symmetryof the points of connection of the position of the respective pistons,causing either too early or too late firing of the cylinder, withconsequent inefliciency and undesirable results.

Attempts have been made to compensate for this variance by varying theangular spacing between the pivotal points of the articulating rods ortheir radial distances from the crankpin, or both, but because ofstructural limitations in the engine design, complete compensation forthis variance has been a practical impossibility and the maximum extentof these variations has been found to be as high as 9, with the resultthat overheating takes place in those cylinders having the earliestfiring timing, thus limiting the capacity of the engine.

In order to compensate for this error in timing, due to difierencesbetween crank-arm position with reference to top dead center position ofthe connecting rods with respect to the master rod axis of pivotation.

Heretofore, the firing interval of cylinders has been regulated by a camand breaker arrange-. ment with the cam having equally spaced lobes andgeared to rotate at a speed sufilcient to fire the cylinders in apredetermined firing order.

Since said cam was ultimately geared to the crankshaft, the provision ofequally spaced lobes resulted'in the firing of the cylinders atuniformintervals as measured by the revolution of the crankshaft fromcenter line to center line oi the cylinders, or, in other words, theignition was taking place at regular intervals in relation to inders,provision is made in the ignition system for causing each cylinder tofire in individually predetermined relation with respect to the topdeadcenter position ofthe corresponding piston. For this purpose, I haveprovided a breaker cam with a plurality of lobes spaced and arranged tocorrespond with the respective angular relations between the connectingrods of successively firing cylinders and having a speed of rotationsuch that each lobe is at the make and break position with respect totop dead center.'

Heretofore, breaker cams for regulating the firing intervals haveusually been mounted onthe magneto rotor shaft; and therefore made witha number of lobes equal to the number of flux changes .per revolution ofthe magneto. Consequently. the cam was generally geared to thecrankshaft at some uneven ratio which would provide for the revolutionof the cam at a rate of speed to provide a make and break of the magnetocircuit to correspond to the crankshaft revolution at successivelyfiring cylinders. accordance with my invention, it is required that thecamshaft be operated at a. speed whereby eachwill permit, to mount thecam on the distributor shaft. In other designs of magnetos, I haveadapted a set of gears to rotate an auxiliary camshaft at the prescribedrate of speed.

By regulating the firing of each cylinder at predetermined intervalswith respect to the top dead center position of each piston, more powerand economy of operation can be obtained, because the maximum sparkadvance can be maintained for each cylinder, which was heretoforeimpossible. This improvement is particularly advantageous in the use ofpresent day high output aviation engines operating with high compressionratios and with the demand for maximum fuel economy.

Although my invention is applicable to radial engines with variousnumbers of cylinders, I have illustrated the same with a seven-cylinderengine of the four-stroke two-cycle type.

Referring to the drawings, wherein like reference characters indicatecorresponding parts throughout the several views:

Fig. 1 is a fractional side elevation view of a seven-cylinder radialengine showing magneto attached;

Fig. 2 is an enlarged elevational view in fraction of the magneto withthe casing partially broken away to show the location of the cam;

Fig. 3 is a detail view showing a breaker unit embodying my invention;

Fig. 4 is an elevational view of a magneto showing parts broken away andin section;

Fig. 5 is a section detail view;

Fig. 6 is a diagrammatic view of my improved cam showing the arrangementof the lobes with relation to the cylinder axes (which are shown indotted lines) when the cylinder including the master connecting rodconstitutes the timing reference;

Fig. 7 is a diagrammatic view similar to Fig. 6 showing the arrangementof the lobes with relation 'to the cylinder axes (which are shown indotted lines) that obtains when a certain cylinder is used for thetiming reference, other than the cylinder including the master rod;

Fig. 8 is an operating diagram of the crankarm and connecting rodsshowing the same in three difierent positions.

In Fig. 1 the magneto ID of standard design, usually with four poles, isgeared to the crankshaft by means of gears II and I2, of such ratio asto rotate the magneto to produce a number of flux changes in tworevolutions of the crankshaft, equal to the number of cylinders. .Ifdesired, the number of poles can be made equal to the number ofcylinders, whereby the time interval of flux change can be regulated sothat the instant of make and break for each cylinder will occur when thevoltage is at its maximum value. In Fig. 2 the magneto casing is cutaway to show the magneto'rotor I3, which is immediately operated by thegear [2, shown in Fig. 1, and drivingly connected to the distributorshaft I4 by the gears l5 and I6, which are of'such ratio as to rotatethe distributor shaft at onehalf engine speed, driving the distributor(not shown). Forward of the gear IS in the housing I1 is the cam l8drivingly connected to the distributor shaft, and the breaker l9.

Fig. 3 shows my improved cam IS with its seven lobes in the conventionalcam arrangement, with breaker is and condenser 20.

The embodiment of my invention in Figs. 4

and 5 is similar to that in Fig. 2, except that the cam is differentlyconstructed and arranged.

In this embodiment the cam 29 is drivingly connected with the rotorshaft 2| instead of with the distributor shaft 22 and rotatably mountedin a housing 23 inclosing the rotor shaft. The housing is illustrated asbeing made integral with the magneto casing but may be made to bedetachable therewith, if desired. As shown, the housing has an upwardlyextending supporting arm 24 provided with a journal for rotatablysupporting the cam. The stub shaft 25, that is preferably made anintegral part with the cam, is supported in the arm 24 of the housing 23by the bearing 26, and driven by the rotor shaft through a pinion 21 inmesh with an internal gear 28 that is preferably made integral with thecam. The gear ratio between the pinion and internal gear is such as torotate the cam at onehalf engine speed.

In Fig. 6, my improved cam is diagrammaticaily represented by the solidline construction. The dotted radial lines, numbered in counterclockwiserotation 1--3--5-724--6, represent the axes of those cylindersrespectively, in a seven-cylinder engine, in their firing order. Thus,the cam is designed to cause each cylinder to fire once in onerevolution, while the engine will have made two revolutions. It is,therefore, seen that the angular distance between the dotted lines.representing the respective cylinder axes on the cam, is one-half of thecorresponding angle between the cylinder axes in the engine. Based onthe variation in the crank-shaft rotation between the crank-arm positionat the top dead center position of the piston and the axes of thecorresponding cylinders, I have modified the cam to provide sectors withlobes spaced at angles equal to the angles between the respectivecrank-arm positions at top dead center positions of the pistons insuccessively firing cylinders and arranged the lobes in the sequence ofthe firing order of the corresponding cylinders.

Based on the study of the engine rotation, hereafter made in connectionwith the description of Fig. 9, these deviations are labeledrespectively 11/2, z'/2, :r/2, 10/2, 2/2, and y/2, wherein a: and :r areequal, 1 and y are equal, and z and z are equal.

It will be noted that there are four different sized sectors or chords,(1, b, c and d, and three chords, 'a', b and c, of the same sizes as a,b, and 0 respectively, but, because of the sequence in rotation, allseven lobes are necessary. However. in an engine having two radial rowsof cylinders, when the master connecting rods are arranged in thecylinders apart, the sequence of spaced lobes repeats itself, and it ispossible to build the cam with but half as many lobes as the number offiring intervals. This is desirable to provide optimum speed ratiorelation between the cam and crank-arm to prevent multiplication oferrors which might occur in the measurement of the variations.

In Fig. 7, the cam has simply been rotated on its hub by the y deviationso as to time the #3 cylinder at zero, that is, with the piston in #3cylinder on top dead center and the modified cam lobe for the #3cylinder placed in the position on the cam shaft corresponding to thecylinder axis, while the master connecting rod is still located in the#1 cylinder. This illustrates a greater deviation than before, becausethe y deviation, which was the largest, is now added to all the. otherdeviations, and the deviations as shown are z/+z'/2. y+-' '/2. y-'v/2,zIz/2, y+y'/2 and 11/2. With my improved cam these deviations areautomatically compensated regardless of cam setting, but with a camofuniform lobes, such a reference for timing as the above would resultin an actual deviation from the correct firing position of the amountindicated.

Fig. 8 represents diagrammatically the paths of the points of connectionbetween the articulating rods and the master connecting rod and thecrank-arm in a revolution of a seven-cylinder radial engine. The axes ofthe cylinders are represented by radiating lines numbered l, 2, 3, i, 5,t, l in counter-clockwise direction. The crankshaft and center of theengine i represented by 30. The master connecting rod 3| is arranged in#1 cylinder and the articulating rods for cylindersv Nos. 2, 3, 4, 5, 6,7 are repreattached to the master connecting rod by the link pins d2,43,44, d5, 46 and 41 respectively at the radial distances 52, 53, 54,55,56, 51 respectively.

The path of the crankspin fil, during a revolution, is the circle Si,and the paths of the link pins 52 to H are the elliptical orbits 62, 68,6t, 65, 6B, 61 respectively. It will be noted that the orbits 62 and t1,t3 and 55, and M and 65 are symmetrical pairs, which is the naturalresult of the master rod crankshaft arrangement with respect to themaster rod.

As set out in the introductory part or this specification, thearticulating rod construction in radial engines causes the pistons toarrive at top dead center position when the crank-arm has revolved adifferent number of degrees than that number measured from cylinder axisto cylinder axis. Thi is evident from an inspection of the relations ofthe pistons, connecting rods and crank-arm in three different positions,1', s and t, of the crank-arm. In the position of the crankarm, asrepresented by position 1' and shown in solid line, the crank-arm to isshown coinci= dental with the master connecting rod and with the axis ofthe cylinder, and the piston is at its top dead center position. As therevolution of the crank-arm progresses toward the next firing Icylinder, #3, the crank-pin describes an arc of the circle 6i and thelink pins proceed in their respective elliptical paths. In the position3, which is represented by dot and dash lines, it will be seen that thelink pin 93, in traversing its orbit 53, is approaching the aixs of itscorresponding cylinder. However, the piston is very near the top deadcenter position because the orbit $3 is now receding towards the centerof firing of the cylinder #3 with reference to top dead center positionof the piston is when the crank-arm has revolved two-sevenths of thecircle from the position when cylinder #1 was firing,

plus the angle 1;.

By a similar construction, each of the angular 'variations of thecrank-arm from the cylinder axes for the top dead center pistonpositions in the deviations .r', 11' and 2' occur when the crankarm hasnot yet reached the axes of the cy1in-.

ders,whereasin cylinders 2, 3 and 4 the crank-arm has gone beyond thecylinder axes. It will be seen from the above explanation that thedeviations of the crank-arm from the cylinder axes at the 1 top deadcenter piston positions vary from nothing at zero and 180 degrees ofrevolution, with respect to the master rod as the timing reference, tomaximums at 90 and 270 degrees of revolution. Applying these angularvariations to the fir ing intervals of the engine, we find that thefirst firing interval from cylinder #1 to cylinder #3, labeled a, ismeasured by the two-sevenths of the circle from cylinder #1 to cylinder#3, plus the angle 1;. The firing interval b between cylinders ured bythe two-sevenths of the circle, plus the.

angles 2: and .r. The firing interval 0' from cylinder #2 to cylinder#4, which is of the same size as firing interval 0, is measured by thetwo sevenths of the circle, plus the angle 2 and minus the angle :0. Thefiring interval 17' from cylinder #4 to cylinder #6 is equal to thefiring interval b and measured by the two-seventhsof the circle, minusthe angles a and 11'. The firing interva1 a from cylinder #6 to cylinder#1, thus completing the firing of all the cylinders and two completerevolutions of the crankshaft, is of the same size as the firinginterval a and measured by the two-sevenths of the circle, plus theangle My improved cam, as previously described in Fig. 6, is constructedwith lobes corresponding to each of the firing intervals as abovedescribed. Since the cam makes but one revolution while the crankshaftis making two revolutions, all the angular variations measuring eachlobe are cut in the engine. Nevertheless, the piston will travel a stillgreater distance from the center of the engine and arrive at its topdead cnter position when the link pin 63 has arrived at the position t,shown in dotted line. In thisposition, the crankpin will have travelledin its circular path beyond the axis of the cylinder. The firinginterhalf, but as illustrated in Figs. 6 and '7, are enlarged two timesfor the purpose of illustration.

In addition to said angular deviations, other considerations such asrate of piston travel as: it approaches top dead center position'mayaflect the ignition compensation desired in individual cylinders. It is,therefore, to be understood that proportional to the said angulardeviations, but

' may be predetermined for eachindividual cylinder, as based on thevarious factors to be considered.

Therefore, ,While in describing the construction and operation of thisinvention, a seven-cylinder radial engine has been used for purposes ofillustration, nevertheless, it is to be understood that my invention maybe used with engines having any given number of cylinders, and thatwhile I have described the invention in connection with a magnetoignition system in which the lobes of the cam provide an open dwell thatis substantially alike for all lobes, it will be understood that theinvention contemplates the use of a battery ignitiOn system, and thatthe dwell, open or closed, for the lobes, may be varied to suit the typeand characteristics of the ignition system. employed, and that theinvention is not limited to the exact structure which has beendescribed, but various modifications may be employed, as will be clearto those skilled in the art after reading this specification, the scopeof the invention being indicated by the accompanying claims.

What I claim is:

1. In combination with an internal combustion engine, having thecrank-arm thereof varying alternately between maximums of opposite signsin its angular relations with respect to the axes of the differentcylinders for the top dead center piston positions thereof,respectively, an ignition system associated with the crank of saidengine, having a cam provided with lobes spaced and arranged tocorrespond with the angular relations between the crank-arm positionsand the axes of successively firing cylinders for the top dead centerpositions of the different pistons, respectively, the number of lobesand the speed of rotation being such that each cylinder is caused to befired by only one lobe.

2. In combination with an internal combustion engine of the articulatingrod type, having the crank-arm thereof varying in its angular relationwith respect to the axis of each cylinder for the top dead centerposition of the piston, an ignition system associated with the crank ofsaid engine, having a cam provided with lobes spaced at anglesproportionate to the angles between the respective crank-arm positionscorresponding to the top dead center piston position of each ofsuccessively firing cylinders, said lobes being so arranged and said cambeing so coupled to the crankshaft that each lobe is at the breakposition when its corresponding-piston is at an individuallypredetermined position with respect to the top dead center thereof.

3. In combination with an internal combustion engine of the articulatingrod type, having the crank-arm thereof varying in its angular relationwith respect to the axis of each cylinder for the Y top dead centerposition of the piston, an ignition system associated with the crank ofsaid engine, having a. cam provided with a number of lobes equal to thenumber of cylinders, said lobes being spaced and arranged to correspondwith the angular relations between the crank-arm positions and the axesof successively firing cylinders for the top dead center positions ofthe different pistons.

4. In combination with an internal combustion engine of the articulatingrod type, having a crank-arm that varies in its angular relation withrespect to the axis of each cylinder for the top dead center position ofthe piston thereof, through a plurality of like series of variationsduring each firing cycle of said engine, an ignition system associatedwith the crank of said engine, having a cam provided with a number oflobes equal to the number of variations in a series of said variations,said lobes being spaced and arranged with respect to the angularrelations between the crank-arm positions and axes of successivelyfiring cylinders for the top dead center piston positions, and means forcausing said cam to rotate a number of revolutions equal to the numberof series of variations during each firing cycle of operation of saidengine.

5. An ignition make and break device for use with an internal combustionengine of the articulating rod type having symmetrically arrangedcylinders and pistons operating therein in out of phase-symmetryrelation, said device comprising cam means having a plurality of lobesarranged in out of phase-symmetry relation corresponding to the out ofphase-symmetry relation' of said engine pistons, and breaker meanscooperating with said cam means to ignite said cylinders.

6. In a magneto ignition system a make and break device for use with aninternal combustion engine of the articulating rod type havingsymmetrically arranged cylinders and pistons operating therein in out ofphase-symmetry relation, said device comprising cam means having aplurality of lobes arranged in out of phase-symmetry relationcorresponding to the out of phase-symmetry relation of said enginepistons, and breaker means cooperating with said cam means to ignitesaid cylinders, said magneto being adapted to operate at a speed tocause a flux change per each cylinder in a complete firing cycle ofengine operation, and said cam means being adapted to operate at a speedto make and break said ignition circuit a number of times in a completefiring cycle of engine operation equal to the number of cylinders.

7. An ignition system for internal combustion engines of the radialcylinder type provided with a master connecting rod and secondaryconnecting rods pivoted thereto, and having non-symmetrical firingintervals due to the irregularities of said connecting rods, including asource of ignition current, means for periodically interrupting the flowof said ignition current and means for distributing said ignitioncurrent to the various cylinders in firing sequence, one of said meansbeing adapted to perform its function in said nonsymmetrical firingintervals to thereby initiate combustion at the same period of the cyclein each cylinder.

JOHN J. ROSE.

